Extrabranchial chemoreceptors involved in respiratory reflexes in the neotropical fish<i>Colossoma macropomum</i>(the tambaqui)
Bibliographic record
Abstract
In a previous study, complete denervation of the gills in the tambaqui Colossoma macropomum did not eliminate the increase in breathing amplitude seen during exposure of this species to hypoxia. The present study was designed to examine other sites of putative O(2)-sensitive receptors that could be involved in this reflex action. Superfusion of the exposed brain of decerebrate, spinalectomized fish did not reveal the presence of central chemoreceptors responsive to hyperoxic, hypoxic, hypercarbic, acidic or alkaline solutions. Subsequent central transection of cranial nerve IX and X, removing not only all innervation of the gills but also sensory input from the lateral-line, cardiac and visceral branches of the vagus nerve, did not eliminate the increase in breathing amplitude that remained following peripheral gill denervation alone. Administration of exogenous catecholamines (10 and 100 nmol kg(-1) adrenaline) to fish with intact brains and minimal surgical preparation reduced both respiratory frequency and amplitude, suggesting that humoral release of adrenaline also could not be responsible for the increase in breathing amplitude that remained following gill denervation. Denervation of the mandibular branches of cranial nerve V and the opercular and palatine branches of cranial nerve VII in gill-denervated fish (either peripheral gill denervation or central section of cranial nerves IX and X), however, did eliminate the response. Thus, our data suggest that hypoxic and hyperoxic ventilatory responses as well as ventilatory responses to internal and external injections of NaCN in the tambaqui arise from O(2)-sensitive receptors in the orobranchial cavity innervated by cranial nerves V and VII and O(2)-sensitive receptors on the gills innervated by cranial nerves IX and X. Our results also revealed the presence of receptors in the gills that account for all of the increase in ventilation amplitude and part of the increase in ventilation frequency during hyperoxic hypercarbia, a group or groups of receptors, which may be external to the orobranchial cavity (but not in the central nervous system), that contribute to the increase in ventilation frequency seen in response to hyperoxic hypercarbia and the possible presence of CO(2)-sensitive receptors that inhibit ventilation frequency, possibly in the olfactory epithelium.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".